Shark Week: What Makes a Shark a Shark?

Published August 11, 2014

Over the years, they’ve (mistakenly) become known for being monster predators—filled to the brim with sharp teeth, muscle and an appetite for flesh—but the truth is, there’s much more to sharks than meets the eye!

Sharks have been on the planet for over 400 million years, predating the dinosaurs by 200 million years! While sharks are some of the ocean’s most powerful, apex predators, they’re no monsters.

Close relatives to rays and skates, sharks are elasmobranchs (cartilaginous fish). Unlike other fish, elasmobranchs do not have swim bladders. Instead, they rely on their rather large, oil-filled livers to maintain buoyancy in the water. In addition to their cartilaginous skeletons, all sharks have 5-7 gill slits on the sides of their head.

Sharks are covered in placoid scales, also known as dermal denticles. Each scale has its own fibrous “tooth” structure. Together, the placoid scales help the shark reduce drag and give their skin its characteristic sandpaper-like quality.

There are 465 known species of shark found worldwide! They range in size from the smallest shark species, the pygmy shark, which measures up to 8 inches in length to the largest, the whale shark, which can grow to be up to a whopping 50 feet in length!

Have a question for our staff about sharks? Ask us in the comments section!